Valve proving system

ABSTRACT

The invention relates to a valve proving system. A duct is connected to the valve casing, between the inlet and outlet to collect leakage. Means is provided to ensure that when the valve is closed the pressure in the duct is initially low and means is also provided to produce a response when the pressure in the duct exceeds a predetermined value.

United States Patent 1191 Smith 1451 Aug. 20, 1974 VALVE PROVING SYSTEM[75] Inventor: William Arthur Smith, London,

England [73] Assignee: Babcock & Wilcox Limited, London,

England [22] Filed: May 12, 1972 [21] Appl. No.: 252,563

[30] Foreign Application Priority Data May 14, 1971 Great Britain15070/71 [52] US. Cl 137/312, 73/46, 137/628 [51] Int. Cl. Fl6k 51/00[58] Field of Search 137/312, 557; 73/405,

[56] References Cited UNITED STATES PATENTS 2,136,519 11/1938 OConnor..25l/25X 310 3 VALVE 8/1968 Grove et a1. 137 312 3,51 1,082 5/1970Lathrop et a1 73/46 3,605,792 9/1971 Westbrook 137/312 FOREIGN PATENTSOR APPLICATIONS 1,211,199 ll/l970 Great Britain 137/312 PrimaryExaminer-William R. Cline Assistant ExaminerRichard Gerard Attorney,Agent, or Firm-Joseph M. Maguire, Esq.; Robert .1. Edwards, Esq.

[57] ABSTRACT 6 Claims, 2 Drawing Figures SOL ENOID OPERATED 7 IS l8THROTTLE KVALVE THROTTLE Kw: LVE 3 2a 5 ll VENTED GAS j Q/cneck VALVE/0115 VALVE fAlR OPERATED VALVE I5 27 PRESSURE sw1Tc1-1 FUEL VALVE #0 /4FUEL VALVE ACTUATOR Pmmanwnzmw 59 SOLENOID OPERATED 3/0 3 VALVE 9%JMQQ/ICHECK VALVE I9 15 30 THRCTTLE KVALVE 2 gg/cnscx VALVE 330 fAlROPERATED VALVE:

l5 PREssuR|-: 0b 1 a SWITCH vsm'en sAs/ l3 FUEL VALVE 0 #0 I2 \IFUELVALVE- 5 ACTUATOR d. I I

VALVE PROVING SYSTEM This invention relates to valve proving systems andderives from a consideration of the problems arising in the design ofgas-fired burner installations.

In a gas fired furnace having a tall flue, the flue, even when thefurnace is idle, will tend to be raised by ambient conditions to atemperature higher than that of the furnace chamber. The resultanttemperature differences will tend to result in currents establishing anegative pressure in the furnace chamber so that if the supply of gas tothe furnace is controlled by a valve, and a leak caused by wear, forinstance, has developed through the valve, then there will be a tendencyfor gas to be drawn into the furnace chamber. If there is no warning ofthe presence of gas in the chamber, and the ignition of the burners isinitiated in the normal way, a risk of explosion arises.

By use of the present invention in association with a gas-fired furnace,for instance, it is possible, should a leak develop in the valvecontrolling the flow of gas to the furnace, to derive an indication ofthe fact so that remedial action can be taken. Apparatus embodying theinvention may, it will be understood, be used in other contexts.

According to the present invention, there is provided a valve having acasing, an inlet to and an outlet from the casing, and means movablewithin the casing between an operative position in which a connectionbetween the inlet and the outlet is established and an inoperativeposition in which the inlet and the outlet are obturated, and a valveproving system including a duct opening into the casing between theinlet and the outlet, means responsive to the pressure within the ductand arranged to produce a response when the pressure in the duct exceedsa certain value, exhaust means associated with the end of the ductremote from the casing that, on actuation, reduces the pressure in theduct and after actuation effects a closure of the end of the duct, andmeans whereby the exhaust means may be actuated when the valve is in itsclosed condition.

By way of example, an embodiment of the invention will now be describedwith reference to the accompanying drawing in which:

FIG. 1 shows schematically, valve proving apparatus, and

FIG. 2 shows a sleeve valve that may be used in a modification of whatis shown in FIG. 1

In this embodiment a double block ball valve is included in the duct 11by which gas is supplied to a furnace. The furnace is not shown in thedrawings but may be assumed to discharge combustion gases through aboiler stack. When the furnace is inoperative, ambient temperatureconditions will tend to lower the pressure in the stack so that there ispositive pressure difference across the valve 10 that tends to draw gasinto the furnace chamber. The valve includes a casing 12 having aspherical cavity and diametrically opposite inlet and outlet openings12a and 12b respectively. A ball 13 is rotatable within the casing 12and is penetrated by a passage that, when the valve is operative,connects the inlet and outlet openings and, when the valve isinoperative, lies transversely of the axisof the openings.

A spindle 14 by which the ball can be rotated is perpendicular to boththat axis and the openings and extends through a seal 14a in the casingand a duct 15 opens into the casing at a point dimetrically opposite theseal. At its other end, the duct opens into a cylinder 16 in which apiston 17 is reciprocable. One or, for safety should one spring fail,several springs (indicated at 18), urge the piston 17 towards-the end ofthe cylinder remote from the end into which the duct opens and a seal 19is formed between the piston and the cylinder. The seal used in theembodiment illustrated is provided by a flexible sleeve fixed at one endto the piston 17 and at the other end to the end of the cylinder 16towards which the piston is urged by the springs. Between its ends, thesleeve is folded upon itself, the position of the fold relatively to theends moving as the piston moves within the cylinder. The cylinder isprovided, at the end to which the duct leads, with a one-way valve 20,flow through which facilitates the movement of the piston towards thatend of the cylinder.

Between the cylinder 16 and the casing 12, the duct 15 includes anon-retum valve 25 and, upstream of that, a diaphgram-controlledisolating valve 26. Between the diaphragm-controlled valve 26 and thecasing 12, a pressure responsive switch 27 is connected to respond tothe pressure in the duct 15 and generate an audible or visible signal ifthe pressure exceeds a certain value.

The operation of the ball valve 10 is controlled pneumatically by airdelivered through an air line 30 from a source (not indicated). Pressurein the line 30 acts through the actuator 34 to rotate the spindle 14against the action of a restoring spring incorporated in the actuator 34and which tends continuously to rotate the spindle 14 in the sense thatcloses the valve 10. Connection between the air line 30 and the sourceis through a solenoid controlled two-way valve 31 which in oneconditionconnects the source to the line and in the other obturates thesource and connects the line to a vent 31a. There extends from the line30 to the end of the cylinder 16, on the side of the piston 17 oppositeto that to which the duct 15 leads, a branch 32 and to thediaphragm-controlled valve 26, a branch 33. Eace of these branchescontains an air flow restrictor 32a and 33a respectively to control thereactions of the piston and the diaphragm-controlled valve to theactuation of the valve that connects the air line 31 to the vent 31a.

Now suppose the furnace is to be brought into operation. The solenoidvalve 31 is operated to connect the air line to the source. The pressurein the line 30 will open the ball valve 10 so that gas flows to thefurnace. Pressure in the branch 33 will cause the isolating valve 26 tosnap shut. Pressure in the branch 32 moves the piston in the cylinder inthe direction that compresses the springs, gas or air on the spring sideof the piston escaping through the pressure relief valve 20. If the ball13 is a close fit in the casing 12 so that no unacceptable leak aroundit has developed, the pressure within the duct 15 will not rise to sucha value as to actuate the pressure responsive switch 27.

the valve 10 has closed. Gas that may have been trapped in the valvewill pass through the duct and escape through the pressure relief valve20. When the pressure in the line has been relieved through the vent31a, movement of the piston 17 under the action of the springs 18, at arate controlled by the setting of the valve 32a, will then act to lowerthe pressure in the duct 15. The position of the piston 17 in thecylinder 16 will be determined by equilibrium between the effect of thesprings and the pressure in the duct 15. Should there be a leakage intothe casing 12 (as a result of wear for instance), between the inlet andthe outlet of the gas control valve 10, gas will leak into the duct andso raise the pressure in the duct. Then the piston 17 will move underthe action of the springs 18 to maintain equilibrium until the piston 17reaches the end of its possible range of travel. Throughout this time,the pressure in the duct 15 is less than that at which the pressureresponsive switch 27 operates. When the pressure increases beyond apredetermined value greater than the pressure that can be maintained bymovement of, the piston, the valve 27 will open and cause an alarm tooperate so that appropriate action can be taken to eliminate the valveor duct leakage indicated by the operation of the alarm.

In a modification of what has been described the diaphragm controlledvalve 26 is replaced by a sleeve valve of which the rod 41 is connectedto be positively moved by rotation of the shaft 14 of the valve 10, theposition of the rod in the sleeve being dependent upon the orientationof the ball 13. The sleeve valve has an inlet 42 to which one part ofthe duct 15 is connected, and an outlet 43, to which the other part ofthe duct 15 is connected, the inlet and outlet being connected orobturated according to the position of the rod 41. The sleeve valve isalso provided with a vent 44. When the gas valve is open thecorresponding position of the rod 41 is such that the inlet 42, outlet43, and vent 44 are closed by the rod 41. As the spindle 14 of the gasvalve starts to rotate in closing the valve, it moves the rod 41 to theposition in which it is shown in the drawing, in which the inlet 42 isconnected to the vent 44, and the outlet 43 is closed. Further rotationof the shaft, to a position in which the inlet 12a and outlet 12b areobturated by the ball 13, causes the rod 41 to move to a position inwhich the inlet 42 and outlet 43 are connected so that movement of thepiston 17 in the cylinder 16 under the action of the springs 18 exhauststhe casing 12. Movement of the ball 13 to its final position isaccompanied by movement of the rod 41 to a position in which it closesboth the inlet 42 and the outlet 43 so that leakage after this into thecasing 12 will create pressure in that part of the duct 15 that liesbetween the casing 12 and the valve 40 which, if the pressure becomeshigh enough, will cause an alarm to be given.

An advantage of the embodiment shown in FIG. 1 over the modification ofFIG. 2 is that it does not require the bracket, and other componentsthat may be required in the latter to establish a reliable connectionbetween the spindle 14 and the rod 41 of valve 40, thus enabling thecomplete assembly of component parts to be erected on a small flat panelwhich may be mounted on pipe bracketing immediately adjacent to the ballvalve and a single connection utilized to make the entry to the ballvalve casing.

In the embodiments that have been described, piston 17 is moved bypressure in the line 30 and once the pressure has been removed, and thepiston has moved to the extreme position to which it is urged by thesprings 18, the increase of pressure in duct 15 will cause an alarm tosound and the apparatus will remain in this condition until remedialsteps are taken. Now it may be that a slow rate of leakage into thecasing, and hence into the furnace, could be tolerated. It is thereforeenvisaged that the piston and cylinder 16 might be replaced by a device,such as an electric pump, which would act to exhause the duct 15 butwhich could be re-activated automatically without the line 30 being putunder pressure after the pressure responsive switch 27 had operated. Inthese circumstances infrequant operation of the alarm would beconsidered tolerable whilst action would be considered necessary if thealarm operated at a rate greater than an allowable maximum.

1 claim:

l. The combination of a fluid flow valve including a casing having aninlet and an outlet opening, a valving member disposed within the casingand movable between open and closed valve positions with respect to saidopenings, a system for removing fluid from within the casing when thevalving member is in closed position, pressure responsive means forventing the system when the fluid pressure therein exceeds apredetermined value, said system comprising wall means defining achamber, duct means flow connecting an end of said chamber with thecasing space intermediate said openings, partition means movable withinthe chamber, and resilient means urging the partition means away fromsaid chamber end, the duct means including an isolating valve having anopen position to establish communication between said chamber and casingsapce, and a closed position to cut off communication therebetween, andpressure responsive means for generating a signal when the fluidpressure within the duct means exceeds a predetermined value, said lastnamed value being less than that required for venting the system, acontrol circuit operatively associated with said fluid flow valve andsystem, and including means for actuating the valving member andisolating valve and partition means, the presence of said actuatingmeans in the control circuit serving to open the flow valve and to closethe isolating valve and to counteract said resilient means and move thepartition means toward said chamber end, and the absence of saidactuating means from the control circuit serving to close the flow valveand to open the isolating valve and to permit the resilient means tourge the partition means away from said chamber end to form a reservoirtherebtween and reduce the pressure within said system.

2. The combination according to claim 1, wherein said actuating means isa pressurized fluid.

3. The combination according to claim 1, including throttling meansdisposed in the control circuit to delay the actuation of said isolatingvalve and partition means.

4. The combination according to claim 1, wherein said resilient meansincludes at least one spring member.

5. The combination according to claim 1, wherein the chamber is in theform of a cylinder and the partition means includes a disc member.

6. The combination according to claim 5, including a flexible sleeveforming a seal between said cylinder and disc member.

1. The combination of a fluid flow valve including a casing having aninlet and an outlet opening, a valving member disposed within the casingand movable between open and closed valve positions with respect to saidopenings, a system for removing fluid from within the casing when thevalving member is in closed position, pressure responsive means forventing the system when the fluid pressure therein exceeds apredetermined value, said system comprising wall means defining achamber, duct means flow connecting an end of said chamber with thecasing space intermediate said openings, partition means movable withinthe chamber, and resilient means urging the partition means away fromsaid chamber end, the duct means including an isolating valve having anopen position to establish communication between said chamber and casingsapce, and a closed position to cut off communication therebetween, andpressure responsive means for generating a signal when the fluidpressure within the duct means exceeds a predetermined value, said lastnamed value being less than that required for venting the system, acontrol circuit operatively associated with said fluid flow valve andsystem, and including means for actuating the valving member andisolating valve and partition means, the presence of said actuatingmeans in the control circuit serving to open the flow valve and to closethe isolating valve and to counteract said resilient means and move thepartition means toward said chamber end, and the absence of saidactuating means from the control circuit serving to close the flow valveand to open the isolating valve and to permit the resilient means tourge the partition means away from said chamber end to form a reservoirtherebtween and reduce the pressure within said system.
 2. Thecombination according to claim 1, wherein said actuating means is apressurized fluid.
 3. The combination according to claim 1, includingthrottling means disposed in the control circuit to delay the actuationof said isolating valve and partition means.
 4. The combinationaccording to claim 1, wherein said resilient means includes at least onespring member.
 5. The combination according to claim 1, wherein thechamber is in the form of a cylinder and the partition means includes adisc member.
 6. The combination according to claim 5, including aflexible sleeve forming a seal between said cylinder and disc member.